In a semiconductor device assembly, an integrated circuit die (also referred to as a semiconductor chip or “die”) may be mounted on a packaging substrate. The integrated circuit die generates heat when electrical current flows through the integrated circuit die. As such, passive and active thermal management devices are used to minimize potentially damaging effects of heat on the device. Such thermal management devices include heat spreading lids, heat sinks, etc. Typically, a heat conducting material is also used to facilitate heat transfer within the package. For example, a thermal interface material (TIM) may be deposited between the integrated circuit die and the heat spreading lid to enhance heat transfer from the integrated circuit die to the heat spreading lid.
However, device packages using TIM may have problems meeting heat dissipation requirements. A conventional TIM is typically made from material with low thermal conductance, such as silicone or epoxy. The thermal conductance of TIM is substantially lower than that of a good thermal conducting metal (e.g., copper), which may result in lower efficiency of heat transfer. For example, the thermal conductivity of the TIM is about 3.8 watts per meter kelvin (W/m-k) while the thermal conductivity of a good heat conductor, such as copper, is about 401 W/m-k. Generally, a low thermal conductivity indicates that a material is a poor conductor of heat, which means the TIM may impede heat transfer from the integrated circuit die.
The presence of air in TIM may also reduce the thermal conductance of the TIM. The thermal conductivity of air is typically lower than the TIM. For example, the thermal conductivity of air is about 0.025 W/m-k. Such low thermal conductance may result in low efficiency of heat transfer. The creation of air bubbles or trapping of air pockets in the TIM usually occurs during the lid attach process. For example, an incorrectly-fitted heat spreading lid over the integrated circuit die may cause trapping of air pockets in the TIM. As such, the heat transfer efficiency of the TIM may be reduced.